Metals (Jun 2018)

Thermal Stability and Lubrication Properties of Biodegradable Castor Oil on AISI 4140 Steel

  • María Teresa Hernández-Sierra,
  • Luis Daniel Aguilera-Camacho,
  • José Eduardo Báez-García,
  • J. Santos García-Miranda,
  • Karla J. Moreno

DOI
https://doi.org/10.3390/met8060428
Journal volume & issue
Vol. 8, no. 6
p. 428

Abstract

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Lubricants have much importance in several industries, principally serving to reduce friction and wear in mechanical elements. In this study, the influence of Castor oil as bio-lubricant on the friction and wear performance of AISI 4140 steel was investigated. For that purpose, pin-on-disk friction tests were conducted according to ASTM G-99, by using pins of tungsten carbide (WC) as counterparts. The experiments were performed at two different temperatures. This work also presents the Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and 1H-NMR analyses for the chemical characterization of oils and a study of their degradation by oxidation. The analysis of the damage caused to steel due to friction was deepened by analyzing its microhardness and microstructure in the worn zone. As a reference, the same experiments were performed with a commercial oil. The friction behavior of 4140 steel/WC with Castor oil lubrication at the two temperatures was notably better than that obtained under the reference oil lubrication. The kinetic friction coefficient (µk) was up to 76% lower. However, a slight increase in steel wear was observed under Castor oil lubrication. Despite this, these results suggest that Castor oil could be used as bio-lubricant in systems which are susceptible to levels of high friction.

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